Question 555Electricity & Electronics - Assistant Engineer

The correct answer is D) the bridge rectifier is uncontrolled and the controller inverter bridge is transistor controlled in terms of switching. This is correct because in a variable speed drive system, the bridge rectifier is typically an uncontrolled rectifier, which converts the AC input to DC. The controller inverter bridge, on the other hand, is a transistor-controlled inverter that converts the DC back to variable frequency AC to drive the motor at the desired speed. The other options are incorrect because A) and C) state that the bridge rectifier is thyristor-controlled, which is not the case in a typical variable speed drive setup. Option B) is also incorrect as the inverter bridge is transistor-controlled, not thyristor-controlled.